The present invention relates to a method and apparatus for permitting exploration of the common bile duct through the cystic duct by use of a malleable stylet disposed in a small diameter probe of an endoscope.
Heretofore, the conventional method and apparatus for examining the common bile duct comprised opening the bile duct and inserting a Bake's dilator within the duct. The Bake's dilator generally comprises a malleable rod having a handle on one end and an enlarged distal end. The rod portion of the dilator may be bent so that the surgeon may hold the handle while the distal end is within the duct. The dilator is passed through the common bile duct, and any stone within the duct will be felt by the surgeon although he cannot see the stone within the duct. Once the stone is detected, it may be removed by either pressing against it with the dilator and moving it down the duct and through the passageway into the intestine or, alternatively, the dilator may be removed and another instrument suitable for gripping the stone may be inserted to grasp the stone and withdraw it through the opening into the bile duct.
While the above-described prior art method and apparatus for exploration of the bile duct has been successfully used, it has many limitations. In the first place, it requires opening of the bile duct itself increasing the risk and duration of the surgery rather than using the already open smaller cystic duct. In addition, the surgeon cannot readily determine whether his operation with the Bake's dilator has successfully removed all stones from the bile duct as, for example, smaller stones may pass around the distal end of the dilator as it is being moved through the bile duct. Thus, the use of the Bake's dilator for biliary tract exploration is not always entirely satisfactory.
Endoscopes have been used extensively in connection with the examination of ducts or passageways within the body. However, heretofore, it has not been possible to provide an endoscope which is entirely suitable for use in connection with determining the condition of the interior of the common bile duct. The problem has been that conventional endoscopic equipment is too large to pass through a normal diameter common bile duct. When the bile duct is abnormally large enough to accept these scopes, there are still problems. The rigid scope with its fixed dimensions can only visualize limited areas of the extremely variable bile duct, while the very flexible scopes are difficult to stabilize and therefore difficult to direct through these serpentine ducts.
In the prior art there have been provided endoscopes with steering means for directing the distal end of the probe on the endoscope. Typical of these devices are the endoscopes disclosed in U.S. Pat. Nos. 3,572,325; 3,739,770; 4,245,624 and 4,351,323. All of the foregoing patents disclosed various types of mechanical means for directing the path of the distal end of an endoscope. While these devices are useful in connection with the use of an endoscope in relatively large ducts, such as the intestine, it is impossible to incorporate such mechanism within an endoscope suitable for passage through a cystic or common bile duct of normal diameter.
U.S. Pat. No. 4,601,283 discloses a probe for an endoscope which is provided with a shape memory alloy whereby the flexible tube may be inserted through the bent portions of a passageway and, when it is desired to give the tube rigidity, a heating wire heats the memory alloy to its original shape to provide rigidity to the flexible end of the probe. This method and apparatus for inserting a probe into a passageway within the body could not be used in connection with examination of the bile duct due to the size constraints of exploratory operations within the bile duct and due to the extreme flexibility of a probe small enough to fit within the cystic duct.